It is known that paraffinic products boiling in the gasoline range can be prepared from a Fischer-Tropsch derived synthesis product. Preparing a gasoline having an acceptable octane number from a Fischer-Tropsch product is however not straightforward. This because the Fischer-Tropsch product as such consists for a large portion of normal paraffins which have a low octane value or contribution. Various attempts have been made to provide a process, which can prepare a gasoline having an acceptable octane value from a Fischer-Tropsch product.
EP-A-512635 discloses a process wherein a gasoline having a motor octane number of 85 is obtained from a Fischer-Tropsch process by means of a hydroisomerisation process. The process also involves separation of normal and iso-paraffins using a zeolite bed.
U.S. Pat. No. 6,436,278 discloses a similar process as EP-A-512635. The examples illustrate that the gasoline as directly obtained in a hydroisomerisation step has an octane number of 43. After enrichment of the gasoline fraction in iso-paraffins the octane number of 68 was obtained.
US-A-20020111521 discloses a process to prepare a gasoline by subjecting a Fischer-Tropsch wax to a so-called Paragon reactor to obtain lower olefins. These lower olefins are subsequently oligomerised to obtain highly branched iso-olefins with a size range of between C12 and C20.
EP-A-454256 discloses a process to prepare lower olefins from a Fischer-Tropsch product by contacting this product with a ZSM-5 containing catalyst at a temperature of between 580 and 700° C. in a moving bed reactor at a catalyst to oil ratio of between 65 and 86 kg/kg.
U.S. Pat. No. 4,684,756 discloses a process to prepare a gasoline fraction directly by catalytic cracking of a Fischer-Tropsch wax as obtained in an iron catalysed Fischer-Tropsch process. The gasoline yield is 57.2 wt %.
A disadvantage of some of the above processes involving hydro-processing is that the isomerised product will be predominantly mono-methylparaffins. Even after enrichment in iso-paraffins, the octane rating remains low.
The object of the present invention is to provide a paraffinic gasoline component having an acceptable motor octane number, and a process to prepare this gasoline from a Fischer-Tropsch product, in a high yield.